1. Field of Invention
Aspects of the present invention relate to data centers containing racks and enclosures used to house data processing, networking and telecommunications equipment, and more particularly to cooling systems and methods used to cool equipment housed by such racks and enclosures.
2. Discussion of Related Art
Equipment enclosures or racks for housing electronic equipment, such as data processing, networking and telecommunications equipment have been used for many years. Such racks are used to contain and to arrange the equipment in small wiring closets as well as equipment rooms and large data centers. In certain embodiments, an equipment rack can be an open configuration and can be housed within a rack enclosure, although the enclosure may be included when referring to a rack.
Over the years, a number of different standards have been developed to enable equipment manufacturers to design rack mountable equipment that can be mounted in standard racks manufactured by different manufacturers. A standard rack typically includes front mounting rails to which multiple units of electronic equipment, such as servers and CPUs, are mounted and stacked vertically within the rack. An exemplary industry standard rack is approximately six to six-and-a-half feet high, by about twenty-four inches wide, and about forty inches deep. Such a rack is commonly referred to as a “nineteen inch” rack, as defined by the Electronics Industries Association's EIA-310-D standard.
Nineteen inch racks are used extensively in data centers and other large facilities. With the proliferation of the Internet, it is not uncommon for a data center to contain hundreds of these racks. Further, with the ever decreasing size of computer equipment, and in particular, computer servers and blades, the number of electrical devices mounted in each rack has been increasing, raising concerns about adequately cooling the equipment.
Heat produced by rack-mounted equipment can have adverse effects on the performance, reliability and useful life of the equipment components. In particular, rack-mounted equipment, housed within an enclosure, may be vulnerable to heat build-up and hot spots produced within the confines of the enclosure during operation. The amount of heat generated by a rack of equipment is dependent on the amount of electrical power drawn by equipment in the rack during operation. In addition, users of electronic equipment may add, remove, and rearrange rack-mounted components as their needs change and new needs develop.
Previously, in certain configurations, data centers have been cooled by computer room air conditioner (“CRAC”) units that are typically hard piped, immobile units positioned around the periphery of the data center room. These CRAC units intake air from the fronts of the units and output cooler air upwardly toward the ceiling of the data center room. In other embodiments, the CRAC units intake air from near the ceiling of the data center room and discharge cooler air under a raised floor for delivery to the fronts of the equipment racks. In general, such CRAC units intake room temperature air (at about 72° F.) and discharge cold air (at about 55° F.), which is blown into the data center room and mixed with the room temperature air at or near the equipment racks.
The rack-mounted equipment typically cools itself by drawing air along a front side or air inlet side of a rack, drawing the air through its components, and subsequently exhausting the air from a rear or vent side of the rack. A disadvantage of the CRAC-type air conditioning system is that cool air is mixed with the room temperature air, which is inefficient. Ideally, to make the system as efficient as possible, and to utilize as little energy and floor space as possible, the highest possible temperature air should be drawn into the CRAC units and the outlet air generated by the CRAC should be a few degrees below room temperature. In addition, airflow requirements can vary considerably as a result of different numbers and types of rack-mounted components and different configurations of racks and enclosures.
For large data centers requiring CRAC units at or near the middle or center of the data center room, delivery of coolant to the CRAC units must be located within the raised floor since it is undesirable to secure coolant piping to the ceiling of the data center due to risks involved with the possible failure of the piping joints. Specifically, with traditional CRAC systems, the piping of the units requires significant cutting and hand soldering of pipes. Leaks are common and leaking water or coolant in a data center may result in risk of damage to equipment housed within the equipment racks. In addition, the potential of earthquakes may shake the pipes and cause the joints to fail. For at least these reasons, most data center designers and operators are unwilling to consider overhead piping for cooling a data center.